A stent is a medical device introduced into a body lumen and is well known in the art. A stent may be delivered in an unexpanded state to a desired location in a bodily lumen and then expanded by an internal radial force. Stents, grafts, stent-grafts, vena cava filters, expandable frameworks, and similar implantable medical devices, collectively referred to hereinafter as stents, have included radially expandable endoprostheses, which have been used as intravascular implants capable of being implanted transluminally.
Esophageal stents have been used to treat patients suffering from a range of malignant and non-malignant diseases. Most commonly, esophageal stents have been associated with the treatment (e.g., palliative) of esophageal cancers. Esophageal stents have also been used to reduce symptoms resulting from non-esophageal tumors that grow to obstruct the esophagus and to treat benign esophageal disorders, including but not limited to refractory strictures, fistulas and perforations. In each of these cases, esophageal stents may provide mechanical support to the esophageal wall, may maintain luminal patency, and/or may alleviate symptoms including pain, choking sensations, and severe difficulty swallowing. Because of the structure of the esophagus and conditions such as peristalsis, esophageal stents have been prone to stent migration. When migration occurs, the patient may experience the return of symptoms and reintervention (e.g., stent repositioning, stent removal) may be required.
One way to reduce the risk of stent migration has been to expose bare metal portions of the stent to esophageal tissue. The open, braided structure of the stent may provide a scaffold that promotes tissue ingrowth into the stent. This tissue ingrowth may aid anchoring the stent in place and may reduce the risk of migration.
In some cases, however, tissue ingrowth has been known to lead to reocclusion of the esophagus, for example, in patients receiving a stent to treat malignant growth. In addition, esophageal stents anchored by tissue ingrowth cannot be moved or removed without an invasive procedure (e.g., causing trauma to a patient). To reduce tissue ingrowth, stents have been covered with a coating (e.g., made of a polymer, etc.) to create a physical barrier between the lumen and the esophageal wall. However, in some circumstance, such stents can have an unacceptable occurrence of migration, as compared to bare metal counterparts.
Some stents are fully degradable and have been designed to be present in a body lumen for a predetermined period of time following delivery and deployment after which the stent degrades. However, these stents do not have control over lumen reocclusion built into its design.
Another way to reduce the risk of stent migration has been to use a flared stent (e.g., in the esophagus). However, stents having flares can have an unacceptable occurrence of migration. Stents have been known to include flares (e.g., flared ends), which include many shapes and both covered and uncovered varieties. Flares have been used to anchor a stent at an implantation site (e.g., in the esophagus) and have been shown to reduce migration. However, further decreases in migration rates are desired.
In one or more applications, removable stents are desired, for example, in applications for treating benign disorders. Some applications of stents include use as a bridge to treatment and less of a palliative measure, due in part to improvements in some cancer therapies and other methods of treating malignant growths. However, efforts to improve removability have been at odds with at least some measures taken to reduce risk of stent migration. Improved stents that reduce trauma during stent removal and improve stent adhesion to the body lumen (e.g., esophageal wall) are desired.
Some fully covered stents have additionally included a second woven-metal layer external to the fully covered stent that may allow tissue ingrowth without allowing tissue overgrowth to occlude the body lumen (e.g., esophagus, etc.). However, the additional scaffolding that allows for tissue ingrowth may undesirably increase the stent profile.
Improved stents with, for example, improved resistance to migration, improved stent adhesion to the esophageal wall, and/or improved removability are desired. Some tracheal stents have incorporated bumps or other surface features into the stent itself or have included a plurality of surface protrusions on the outer surface of the stent.
Without limiting the scope of the present disclosure, a brief summary of some of the claimed embodiments is set forth below. Additional details of the summarized embodiments of the present disclosure and/or additional embodiments of the present disclosure may be found in the Detailed Description of the Disclosure below. A brief abstract of the technical disclosure in the specification is also provided. The abstract is not intended to be used for interpreting the scope of the claims.